Method of making molded articles.



HEINRICH DRESLER, ()FLDREUZTHAL, GERMAN Y, ASSIGNOR '10 CflLN-MUSEN BERGWERKS AGTIEN-VEREIN, OF CREUZTHAL, GERMANY.

m'rnon OF MAKING MGLDED ARTICLES.

- Specification of Letters Patent.

' Fatented Jam 14, 1 908.

Application filed December 8. 1906. Serial No. 346.973-

' have invented certain new and useful .lm-

is shortened, and on the other hand thicker sorption ofcarbonicfacid; All

slag, grind it, mix it with water, mold the acid on'the material treated. The object of provements inMethods of Making Molded Articles; and I do hereby declare the following to be a full, clear, and exact description I of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to a method of mak* ing molded articles, without the addition of lime. In carrying out my invention 1 take mass thus obtained, place the molded articles in a chamber, establish a vacuum in said chamber and then introduce carbonic acid gas into said chamberl I The invention consists in a vacuum being produced in the hardening chamber, boiler or the like, before or during the action of carbonic acid or of gases containing carbonic producing a. vacuum is to insure that the carbonic acid should penetrate more quickly and deepl into the interior of the molded articles, w ereby on the one hand the process molded articles can be hardened right through.

Hitherto the air contained inthe molded articles offered resistance to the penetration of carbonic acid, and gave place to the same only in a very gradual manner by diffusion. lf howeven-a vacuum is producedin the hardening chamber, the an ,is drawn out from the moldedv articles, the partially evaporated water of the said articles carrying the airwith it. If'carbonic acid is then introduced, it will be at once drawn right into the interior 'oithe molded articles, and in that way a stone block or-article of any desired sha e such as pipes, ilagstones, etc., is readily 0 tained hardened throughout.

A vacuum can be produced in various ways, for instance, by a water jet pump or by acompressor with inverted action, etc. It can, however, be also reduced by'closing' the hardening boiler on 0th sides after the introduction ofthe carbonic acid, and allowing a vacuum to be formed by the abthese math ods' can be combined in any desired manner. For instance, first air can be driven out from the hardening vessels charged with molded articles, by quickly forcing iii carbonic acid, then the vessel is closed, whereupon a vacuum is very quickly produced by absorption of the carbonic acid. The air contained in the article partly escapes at that time and can be drawn out almost entirely by means of an air pump or the like. This process can be repeated several times if desired. The

latter is specially advisable where the treatment-is cil'ected not by means of pure carbonic acid, but by means of gases containing carbonic acid. After the contents of the gas mixture in carbonic acid have been absorbed, the resulting inoperative gases are pumped out, and after a vacuum has been produced, operative gas miuture is introduced again, and so on, until no more decrease of pressure takes place in the interior of the hardening vessels by abso tion of carbonic acid, which is the sign t at the process is completed. The pressure in the hardening vessel is preferably read b means of a pressure gage outside the vesse so that the process can be controlled, and uniform results obtained.

The vacuum production and the introduction of carbonic acid can be regulated automatically, for instance, by means of a mercury column which isforced upwardswhen vacuum is produced, and at a certain level closes contact in'a-n electric circuit by means of which the air pum is stopped, and at the same time the inlet or'carbonic acid, or for operative gases, is opened. After these have reached'a certain'pressure, another mercury column-which is now forced upwards, closes another electric circuit which can shut off the supply of carbonic acid,and'so on. The regulation can also beefiected mechanically by. means of valves arranged on the inlet open-' ,ing, closing-or opening when the pressure same, placing the-molded, articles in a c am- 1 and finally introducin said chamber, substantially as described; 2. The process of making mottled articles;

'ber, establishing a vacuum insaid chamber, carbonic acid mtQ which consists in grlnding slag Without the I In testimonywheroof, lailfixmy signature,

addition of lime, mixing the ground material in presence of two Witnesses.

witllwater and moldinmit placing the moldw Y w ed articles in a challlbr, establishing a H1 DRESLER' R Vacuum in said chamber, and allowing car- Witnesses-z bonic acid gas to flow into said chamber, sub- BESSIE F. DUNLAP,

stantially as described. LpUIs VANDORN. 

